1. Field of the Invention
The present invention relates to a recording head and a recording apparatus. More specifically, the present invention relates to a recording head and a recording apparatus wherein the recording head comprises a plurality of temperature sensors and recording units having temperature adjusting heaters.
Note that the term "record" used relating to the present invention not only describes meaningful images such as characters or shapes to be provided to recording media, but the description thereof also encompasses providing to the same of meaningless images, such as patterns.
Also, note that the present invention is applicable to various apparatuses, such as printers, photocopiers, facsimile apparatuses having communication systems, word processors having printer devices, and the like, which perform recording on recording media such as paper, thread, fiber, cloth, leather, metal, plastic, wood, glass, ceramics, and the like, and that the present invention is further applicable to industrial recording apparatuses which are compounded combinations of various types of processing apparatuses.
2. Description of the Related Art
Generally, ink-jet heads used for ink-jet printing apparatuses are such wherein, for example, a number of nozzles corresponding to a maximum of around 128 bits are provided, which are scanned in a direction orthogonal to the direction of feeding of the recording paper serving as a printing medium, thus forming an image. It has also become possible to further improve the through-put of printing by means of further increasing the number of nozzles and making the head lengthy in configuration. However, making the head lengthy requires a total number of nozzles in the thousands, which has been a problem as compared to known serial printer heads, in that the manufacturing cost is increased, as well.
Methods have been proposed to deal with such problems, wherein, e.g., a plurality of elemental substrates are arrayed with good precision, these elemental substrates being comprised of electro-thermal converting devices or functional devices for serving as recording devices for causing ejecting of ink. Such an arrangement enables usage of elemental substrates with built-in electro-thermal converting devices or functional devices as line heads. The advantages of employing elemental substrates with built-in electro-thermal converting devices or functional devices are: reduced costs due to simplification in mounting, increase in yield, and further, enabling usage of temperature sensors utilizing semiconductors.
With such known line heads wherein elemental substrates are arrayed as described above, the increase in the number of terminals for connectors provided to the purpose of electric connection between the arrayed elemental substrates and portions other than the head has been a problem, and this along with other problems has made usage of temperature sensors on all of the arrayed elemental substrates difficult.
FIG. 14 and FIG. 15 illustrate the construction of a line head according to the related art. FIG. 14 is a perspective view of the overall configuration of a line head, wherein the head 30 is comprised of a metal base 1 such as aluminum, upon which are formed a plurality of elemental substrates 14 in a row array, upon each which elemental substrates are formed an electro-thermal conversion device (not shown), a temperature sensor, a heat-retaining heater, and the like. Further provided on the substrate 14 is an ink channel comprising ink-ejecting nozzles, and a top plate 3 forming an ink liquid chamber for supplying ink to be ejected. Orifices 42 from which ink is discharged are opened on the orifice plate surface of the front side of the top plate 3. Springs 43 and a spring fixing member 44 are provided in order to fix this top plate 3. The ink is supplied to the ink liquid chamber of the top plate 3, by means of the ink channel member 5, via a connector 45 connected to the recording apparatus main unit. Also, a print substrate 2 is provided upon the base 1, with the electrodes of the print substrate 2 being electrically connected to the wiring of the substrate 14 by means of wire bonding. Further provided to the side surface of the print substrate 2 are connecting electrodes 10 for performing electrical connection with the recording apparatus main unit (hereafter referred to simply as "main unit").
FIG. 15 is a schematic block constructional diagram of such a head 30. In the example illustrated in this Figure, eight elemental substrates 14 are provided, with four of these elemental substrates 14 further comprising temperature sensors of which output is obtained therefrom. For example, in the case of using a line head comprised of nozzles arrayed the full width of A4 size recording paper as the head 30, approximately 3,000 or more become necessary, so that the total number of elemental substrates 14 each provided with 128 electro-thermal converting devices required for such an arrangement is approximately 25. Accordingly, the number of terminals required to extend the temperature sensor terminals and heat-retaining heater terminals from all of these is 80 or so, and it has been quite difficult to provided such a number of terminals on a head.
With the above-described line head 30 comprised of an array of a plurality of elemental substrates 14, each substrate 14 is die-bonded onto the base 1 formed of aluminum or the like, using thermal-conductive adhesive agent. However, each of the elemental substrates 14 a thermally insulated. Accordingly, irregularities in the position of each of the elemental substrates 14 or the thickness of the adhesive agent applied to the base for fixing the substrate into the base may cause different thermal properties among each of the elemental substrates 14. Hence, it has been known that the temperature change may not be correctly detected depending on the substrate 14, if each of the temperature sensors of all of the elemental substrates 14 cannot be used for highly precise head temperature control.
Also, when a user creates a document, it is generally true that the position of characters, diagrams, and the like are often fixed with respect to the location thereof. Further, in the case of line heads, the printing region of each of the nozzles is fixed, so the change in image duty distribution is small compared to that with serial heads according to the scanning method, thus increasing irregularity in rising of temperature. With such line heads temperature control of the elemental substrates 14 can be effectively performed with high precision by means of increasing the number of times of reading the output of the temperature sensors, but depending on the capabilities of the CPU used or the load of the processing contents, sufficient timing may not be able to be obtained necessary for reading the output of the temperature sensors. Moreover, since there is the possibility that the thermal properties of each of the elemental substrates 14 may differ due to the abovedescribed reasons, it is preferable that each of the heat-retaining heaters provided to each of the elemental substrates 14 be independently controlled in order to perform temperature control in an effective manner, however, since there is a limit to the number of terminals for connectors as described above, realizing such an arrangement has been quite difficult.